Date of Award


Degree Name

Master of Arts


Biological Sciences

First Advisor

Merrill R. Wiseman

Second Advisor

Dr. Imy Holt

Third Advisor

Dr. Thane Robinson

Access Setting

Masters Thesis-Open Access



Many investigations have been conducted in the field of soil microbiology during the past.six decades. Most notable among the contributors is S. A. Waksman whose voluminous works have established many of the procedures used in microbial analyses of soil. Yet, the one fact that is foremost to any reviewer of the literature covering this field is that no standardization of techniques for soil analyses exists. The following presentation deals with one method used to estimate the number of bacteria and actinomycetes in soil.

The use of Tris(hydroxymethyl)aminomethane (hereafter referred to as "Tris") is not new. Tris currently is used in many labors.- tories as a buffer in tissue culture systems. In 1960, however, Ohlsson (16) showed that Tris increased coliform indices when employed as the diluent in testing water by the multiple-tube dilution method. Ohlsson hypothesized that Tris possesses dispersion properties and a "protective colloid" effect ·on attenuated coliforms. Since random distribution of organisms is essential in the plating of soil microbes for quantitative studies, the writer felt that Tris might increase the dependability of resul·ts when employed as the diluent in replicate platings of soil bacteria and actinomycetes.

Included in

Biology Commons